GNU Units is described as 'The Units program converts quantities expressed in various scales to their equivalents in other scales. The units program can handle multiplicative scale changes as well as nonlinear conversions such as Fahrenheit to Celsius or wire gauge' and is an app in the Education & Reference category. There are more than 10 alternatives to GNU Units for a variety of platforms, including Online / Web-based, Android, Windows, Android Tablet and iPhone. The best alternative is Wolfram Alpha, which is free. Other great apps like GNU Units are Qalculate! (Free, Open Source), Windows Calculator (Free, Open Source), Insect (Free, Open Source) and Calculator (Free).
Wolfram Alpha is a "Computational Knowledge Engine" - different from a search engine, it answers factual queries directly by computing the answer from structured data, rather than providing a list of documents or web pages that might contain the answer.
Qalculate! is a multi-purpose cross-platform desktop calculator. It is simple to use but provides power and versatility normally reserved for complicated math packages, as well as useful tools for everyday needs (such as currency conversion and percent calculation).
A simple yet powerful calculator that includes standard, scientific, and programmer modes, as well as a unit converter. It's the perfect tool to add up a bill, convert measurements in a recipe or other project, or complete complex math, algebra, or geometry problems.
High precision scientific calculator with full support for physical units. - Evaluation of mathematical expressions - Parsing and handling of physical units (All SI units, imperial units, time-based units, ..
Rule of 3 Calculator is a portable tool that allows you to apply the mathematical Rule of Three in an easier, faster and more practical way! In order to represent decimal numbers, you must use "." instead "," (Example: 1.5 _ 2.33 _ 5.34687)